1. Field of the Invention
The present invention relates to devices for orienting a light beam in a number of different directions. The invention is more particularly concerned with devices of this type which produce a distribution of the beam in three channels by means of a rotating mirror.
2. Description of the Prior Art
Three-channel optical distributors are already known and are employed, for example, in certain x-ray devices for orienting the light beam produced by the x-radiation/light-radiation converter towards various devices for processing light images. By way of example, these devices consist of a video camera alone, a photographic camera or else a movie camera. Thus it is a usual practice to obtain simultaneously an image on the video camera and the photographic camera or on the video camera and the movie camera, or else an image on the video camera alone.
The schematic FIGS. 1a-1c and 2a-2b of the accompanying drawings show two known ways of constructing three-channel optical devices of this type.
In FIG. 1a-1c, the optical distributor comprises two semi-reflecting mirrors 10 and 11 which pivot respectively about two axes 12 and 13 perpendicular to the plane of the drawing. These two axes 12 and 13 are located on each side of the path of a light beam 14 to be deflected.
In the position of the mirrors of FIG. 1a, the mirror 11 is in a position parallel to the beam 14 and does not intercept this latter whilst the mirror 12 is inclined at 45.degree. with respect to the beam. This mirror deflects a portion of the beam 14 in the direction B which is at 90.degree. with respect to that of the incident beam 14. The other portion passes through the mirror 10 in the direction A.
In the position of the mirrors of FIG. 1b, the mirror 10 is in a position parallel to the beam 14 and does not intercept this latter whilst the mirror 11 is inclined at 45.degree. with respect to the beam. In this case, one portion of the beam 14 is deflected in the direction C which is at 90.degree. with respect to that of the incident beam 14 and at 180.degree. with respect to the direction B. The other portion of the beam passes through the mirror 11 in the direction A.
Finally, in the position of the mirrors of FIG. 1c, the two mirrors 10 and 11 are both parallel to the beam 14 and do not intercept it. In this case, the incident beam 14 is not reflected by a mirror and is therefore not deflected.
The optical distributor which has just been described offers the advantage of being compact but calls for two mirrors, two rotation mechanisms and two rotation motors with accurate positioning in order to reproduce the same angle of slope of the mirrors.
Another three-channel distributor in accordance with the prior art will be described with reference to FIG. 2a and 2b. This distributor has a semireflecting mirror 20 which is inclined at 45.degree. with respect to an incident beam 21. This mirror is fixed on a rotary turret 22 which is rigidly fixed to an arm 23. Said arm pivots about a shaft 24 which is parallel to the beam 21. In regard to the turret 22, this latter is capable of rotating about the axis of the beam 21.
In the position of FIG. 2a, part of the incident beam 21 is transmitted in the direction A and the remainder is deflected in the direction B at right angles to the direction of the incident beam.
If the turret 22 rotates through an angle of 90.degree. in the direction of the arrow 25, part of the incident beam is transmitted in the direction A and the remainder is deflected in the direction C at right angles to the direction of the incident beam and to the direction B.
On the other hand, if the turret rotates through an angle of 90.degree. in the direction opposite to the arrow 25, part of the incident beam is transmitted in the direction A and the remainder is deflected in the direction D at right angles to the direction of the incident beam and to the direction B.
Finally, the pivotal displacement of the arm 23 about the shaft 24 in the direction of the arrow 26 withdraws the turret 22 from the path of the incident beam 21 and this latter is therefore transmitted directly towards A without attenuation.
The optical distributor of FIG. 2 makes it possible to obtain four different optical channels, which is not necessary in the case of an x-ray apparatus but the distributor requires two rotation motors, namely one for the turret 22 and the other for the arm 23 as well as their associated mechanism. Furthermore, the movement of withdrawal of the turret results in substantial overall size.
The aim of the present invention is therefore to provide a rotating-mirror optical distributor which is not subject to the above-mentioned disadvantages of distributors of the prior art and which is of simple and rugged construction.